McLEAN, Va. (AP) -- In an anonymous industrial park in Virginia, in an unassuming brick building, the CIA is following tweets - up to 5 million a day.

At the agency's Open Source Center, a team known affectionately as the "vengeful librarians" also pores over Facebook, newspapers, TV news channels, local radio stations, Internet chat rooms - anything overseas that anyone can access and contribute to openly.

From Arabic to Mandarin Chinese, from an angry tweet to a thoughtful blog, the analysts gather the information, often in native tongue. They cross-reference it with the local newspaper or a clandestinely intercepted phone conversation. From there, they build a picture sought by the highest levels at the White House, giving a real-time peek, for example, at the mood of a region after the Navy SEAL raid that killed Osama bin Laden or perhaps a prediction of which Mideast nation seems ripe for revolt.

Yes, they saw the uprising in Egypt coming; they just didn't know exactly when revolution might hit, said the center's director, Doug Naquin.

The center already had "predicted that social media in places like Egypt could be a game-changer and a threat to the regime," he said in a recent interview with The Associated Press at the center. CIA officials said it was the first such visit by a reporter the agency has ever granted.

The CIA facility was set up in response to a recommendation by the 9/11 Commission, with its first priority to focus on counterterrorism and counterproliferation. But its several hundred analysts - the actual number is classified - track a broad range, from Chinese Internet access to the mood on the street in Pakistan.

While most are based in Virginia, the analysts also are scattered throughout U.S. embassies worldwide to get a step closer to the pulse of their subjects.

The most successful analysts, Naquin said, are something like the heroine of the crime novel "The Girl With the Dragon Tattoo," a quirky, irreverent computer hacker who "knows how to find stuff other people don't know exists."

Those with a masters' degree in library science and multiple languages, especially those who grew up speaking another language, "make a powerful open source officer," Naquin said.

The center had started focusing on social media after watching the Twitter-sphere rock the Iranian regime during the Green Revolution of 2009, when thousands protested the results of the elections that put Iranian President Mahmoud Ahmadinejad back in power. "Farsi was the third largest presence in social media blogs at the time on the Web," Naquin said.

The center's analysis ends up in President Barack Obama's daily intelligence briefing in one form or another, almost every day.

After bin Laden was killed in Pakistan in May, the CIA followed Twitter to give the White House a snapshot of world public opinion.

Since tweets can't necessarily be pegged to a geographic location, the analysts broke down reaction by languages. The result: The majority of Urdu tweets, the language of Pakistan, and Chinese tweets, were negative. China is a close ally of Pakistan's. Pakistani officials protested the raid as an affront to their nation's sovereignty, a sore point that continues to complicate U.S.-Pakistani relations.

When the president gave his speech addressing Mideast issues a few weeks after the raid, the tweet response over the next 24 hours came in negative from Turkey, Egypt, Yemen, Algeria, the Persian Gulf and Israel, too, with speakers of Arabic and Turkic tweets charging that Obama favored Israel, and Hebrew tweets denouncing the speech as pro-Arab.

In the next few days, major news media came to the same conclusion, as did analysis by the covert side of U.S. intelligence based on intercepts and human intelligence gathered in the region.

The center is also in the process of comparing its social media results with the track record of polling organizations, trying to see which produces more accurate results, Naquin said.

"We do what we can to caveat that we may be getting an overrepresentation of the urban elite," said Naquin, acknowledging that only a small slice of the population in many areas they are monitoring has access to computers and Internet. But he points out that access to social media sites via cellphones is growing in areas like Africa, meaning a "wider portion of the population than you might expect is sounding off and holding forth than it might appear if you count the Internet hookups in a given country."

Sites like Facebook and Twitter also have become a key resource for following a fast-moving crisis such as the riots that raged across Bangkok in April and May of last year, the center's deputy director said. The Associated Press agreed not to identify him because he sometimes still works undercover in foreign countries.

As director, Naquin is identified publicly by the agency although the location of the center is kept secret to deter attacks, whether physical or electronic.

The deputy director was one of a skeleton crew of 20 U.S. government employees who kept the U.S. Embassy in Bangkok running throughout the rioting as protesters surged through the streets, swarming the embassy neighborhood and trapping U.S. diplomats and Thais alike in their homes.

The army moved in, and traditional media reporting slowed to a trickle as local reporters were either trapped or cowed by government forces.

"But within an hour, it was all surging out on Twitter and Facebook," the deputy director said. The CIA homed in on 12 to 15 users who tweeted situation reports and cellphone photos of demonstrations. The CIA staff cross-referenced the tweeters with the limited news reports to figure out who among them was providing reliable information. Tweeters also policed themselves, pointing out when someone else had filed an inaccurate account.

"That helped us narrow down to those dozen we could count on," he said.

Ultimately, some two-thirds of the reports coming out of the embassy being sent back to all branches of government in Washington came from the CIA's open source analysis throughout the crisis.